Давай выполним вычитание и рассуждать вслух.
- 12 - 5 = 12 - (2 + 3) = (12 - 2) - 3 = 10 - 3 = 7
- 11 - 4 = 11 - (1 + 3) = (11 - 1) - 3 = 10 - 3 = 7
- 14 - 6 = 14 - (4 + 2) = (14 - 4) - 2 = 10 - 2 = 8
- 12 - 8 = 12 - (2 + 6) = (12 - 2) - 6 = 10 - 6 = 4
- 16 - 9 = 16 - (6 + 3) = (16 - 6) - 3 = 10 - 3 = 7
- 15 - 7 = 15 - (5 + 2) = (15 - 5) - 2 = 10 - 2 = 8
- 17 - 8 = 17 - (7 + 1) = (17 - 7) - 1 = 10 - 1 = 9